Nitrogen For Corn Production

Transcription

1 Nitrogen For Corn Production John Sawyer Professor and Soil Fertility Extension Specialist Department of Agronomy Iowa State University

2 Why Nitrogen Is Applied For Corn

3 Corn Yield Response Corn Yield, bu/acre Seven N Rate by Crop Rotation Sites (81 Site-Years) SC and CC Rotations SC CC SC Yield at EONR: 182 bu/acre SC EONR: 156 lb N/acre CC Yield at EONR: 155 bu/acre CC EONR: 192 lb N/acre Nitrogen Rate, lb N/acre

4 Soil Carbon and Nitrogen Response Corn-Soybean Continuous Corn Change in Soil Organic Carbon (mg C kg soil -1 y -1 top 15 cm) Sutherland Nitrogen Fertilizer Input to Maize (kg N ha -1 ) Change in Soil Nitrogen (mg N kg soil -1 y -1 top 15 cm) Sutherland Nitrogen Fertilizer Input to Maize (kg N ha -1 )

5 Nitrogen Use Efficiency

6 Data Source: USDA-NASS, TVA, AAPFCO

7 Corn Grain N Removal vs. N Application Iowa example vs bu/acre vs. 171 bu/acre yield 87 lb N/acre vs. 91 lb N/acre in grain harvest 120 lb N/acre vs. 139 lb N/acre application 0.73 ratio vs ratio (grain N to applied N ratio) 0.82 lb N/bu vs lb N/bu 85% N to planted corn acres per ground water protection act reporting method

8 Nitrogen Use Efficiency (NUE) and Yield With Increasing N Rate Corn Following Soybean NUE (bu increase/lb N applied) NUE Grain Yield AONR EONR Grain Yield (bu/acre) Nitrogen Rate (lb N/acre) Iowa Sites. Yield/Agronomic Efficiency.

9 Cropping System

10 Data Source: USDA-NASS, TVA, AAPFCO

11 Influence of Cropping System On Nitrate-N Concentration In Tile Drainage System mg NO - 3 N/L (flow weighted) Cont. Corn Corn Sb Sb Corn Alfalfa CRP Gyles Randall, Univ. of Minnesota, Lamberton

12 Influence of Cropping System and N Management On Nitrate-N In Tile Drainage Year Crop Fall Fall + NS Spring 40/60 Split lb NO 3 Leached Corn Soybean Corn Soybean Corn Soybean Corn Soybean Corn Total Soybean Total Corn Total lb N/acre as NH 3 ; Total N applied 1,080 lb since 1987 Waseca, MN, Webster cl

13 The Open System and Natural Nitrogen Processing

14 Nitrogen Cycle N 2, N 2 O, NO Atmospheric Nitrogen Gas Air is 78% N 2 NH 3 Volatilization Biological Fixation Industrial Fixation Urban Crops Livestock Food Sewage Sludge Crops Nitrogen Fertilizer Denitrification Plant Uptake Soil Organic Matter (98% of Soil N) Manure Nitrate (NO 3- ) Ammonium (NH 4+ ) Leaching & Tile Flow Nitrification

15 Influence of Precipitation on Nitrate-N In Tile Drainage (180 lb N/acre/yr) Year Apr. Oct. Rainfall Drainage Conc. Flux Inches mg/l lb/acre Normal = 25.2 in. Gyles Randall, Univ. of Minnesota, Waseca

16 Nitrogen Rate Reduction Potential to Reduce Nitrate Losses in Tile Drainage Iowa Tile Flow Nitrate-N Concentration -- Iowa SC Return to N Nitrate-N, mg/l Tile Flow Nitrate-N Net Return Net Return To N, $/acre $0.60/lb N; $6.00/bu Nitrogen Application Rate, lb N/acre

17 Fertilizer Derived N Recovered After Corn Harvest Long Term Continuous Corn Four-Foot Post-Harvest Soil N. Fertilizer Derived Soil Derived N Rate Mineral Organic Mineral Organic Mineral lb N/acre lb N/acre % of applied N lb N/acre Stevens et al. (2005). Univ. of Illinois

18 Corn N Uptake Stevens et al. (2005) Univ. of Illinois Corn N Uptake (lb N/acre) Total N Soil-Derived N Fertilizer-Derived N N Applied Annually (lb N/acre)

19 Corn Productivity and Nitrogen Response

20 Yield and Response to Nitrogen Vary Across Years 300 Ames - SC 250 bu/acre Y-EONR Y-MRTN 0 Year

21 Corn Nitrogen Uptake and Composition Grain PMR 1009; Abendroth et al., 2011

22 Management to Change Nitrate-N Losses

23 Nitrogen Management Land Use Edge of Field Nitrogen Reduction Practices Practice % Nitrate N Reduction [Average (Std. Dev.)] % Corn Yield Change Timing (Fall to spring) 6 (25) 4 (16) Nitrogen Application Rate Depends on starting point Nitrification Inhibitor 9 (19) 6 (22) Cover Crops (Rye) 31 (29) 6 (7) Perennial Land retirement 85 (9) Perennial Energy Crops 72 (23) Extended Rotations 42 (12) 7 (7) Drainage Water Mgmt. 33 (32)* Shallow Drainage 32 (15)* Wetlands 52 Bioreactors 43 (21) Buffers 91 (20)** *Load reduction not concentration reduction **Concentration reduction of that water interacts with active zone below the buffer

24 Nitrogen Reduction Scenarios Statewide Nitrate-N Reduction Practice/Scenario % (from baseline) Baseline Cover crops (rye) on all CS and CC acres 28 Nitrogen Management Reducing nitrogen application rate from background to the MRTN 133 lb N/acre on CB and to 190 lb N/acre on CC 9 (in MLRAs where rates are higher than this) Sidedress all spring applied N 4 Using a nitrification inhibitor with all fall applied anhydrous ammonia fertilizer 1 Moving fall anhydrous ammonia fertilizer application to spring preplant 0.1

25 Nitrogen Management is a Challenge Corn has a high N demand Need N fertilization for profitable production Crops are grown in an open soil system Need to maintain soil N and C resource Corn and soybean are in high demand Corn and soybean are annual crops Perennial crops can significantly reduce nitrate-n losses; but need market for profitability

26 Nitrogen Management is a Challenge Meeting EPA drinking water standard, Gulf hypoxia size, and/or nutrient criteria Different goals and scales Different timelines Different expectations What combination of agronomic, edge-offield, and land use practices can be implemented to meet these goals Water vs. air quality effects